that's not the point
Everyone is getting waaay off track on this. Despite what the governator said in his press release, microstamping has nothing to do with criminal investigation or crime reduction.
Any sentient individual should immediately question why someone intending to commit a crime would intentionally leave evidence so easily linking his presence to the crime scene. Why would any lawmaker think this will actually reduce crime? Do criminals routinely use guns registered in their name and just drop their business cards at the scene of a crime? Of course not - criminals use stolen guns, stolen cell phones, stolen cars, stolen whatever so they're not so easily caught. The intent of this law is to reduce the number of firearms sold in CA, through manufacturer disinterest or increased prices due to compliance with this new law. And as CA goes, so goes the country.
The intent is also to harass legal gun owners, by having their fired brass show up in all kinds of places where their brass ought not to. Don't think of crime scenes - think of school playgrounds. Day care centers. Think of the children. I found brass from your gun in my child's sandbox. How do you plead?
Next: once it's discovered that the microstamping surfaces eventually wear to the degree that they no longer cause readable imprints, there will be legislation introduced that will require periodic inspections of firearms to ensure they remain "safe" i.e. in compliance with the law. When the identifying marks on firing pins, breech faces, or whatever wear away those components will have to be replaced if you want to keep your gun in service. Otherwise the gun will be considered "unsafe" subjecting you to penalties for its possession. It's not a logical stretch - if microstamping is "good" then properly applied imprints will be required as a continued maintenance function. Your 2A rights aren't being infringed, this is just an administrative procedure to ensure compliance with a "good" law, like a NICS check. The fact that it may cost a lot of money or render firearms useless after a short time doesn't infringe upon your rights. It just costs you a little more money (so they'll say). I don't know how many fired rounds will cause the imprinted surfaces to become unreadable but I imagine the number is less than tens of thousands.
Of course the criminals won't care to keep their firearms "safe" in compliance with the law. So, who's the intended target of this law? You: the law abiding gun owner.
As always: Gun control is not about guns. It's about control. Microstamping is a very very odious can of worms.